Low-speed permanent magnet motor with oil-cooled stator core and axial ventilation cooling system

Abstract

The present invention discloses a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system within the stator core, which relates to the field of electric motors. To address the low power density and high component temperatures of existing low-speed permanent magnet motors, the present invention comprises parallel axial oil passages within the stator core, oil tanks mounted on both ends of the stator core, n permanent magnets mounted in the rotor slots, m circular slots formed on the outer surface of each rotor pole body, a damping bar mounted every other circular slot, and slots between adjacent damping bars remaining vacant. The damping bars are connected to damping end rings within the regions at both ends of the rotor pole body, a push-in fan mounted on the outer surface of one damping end ring, and an exhaust fan mounted on the outer surface of the other damping end ring, axial ventilation holes formed in the support plate, and axial fans mounted on both sides of the rotating shaft. The present invention improves the generator's power density and cooling efficiency, and has a simple structure and is easy to implement.

Description

Technical Field

[0001] The invention relates to a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in a stator core, belonging to the field of motors. Background Art

[0002] Low-speed permanent magnet motors have a wide range of applications, playing a vital role in the machinery and equipment manufacturing industry, machine tools, heavy mining machinery, power machinery, and petroleum machinery. Currently, low-speed, high-torque transmission systems still primarily utilize the traditional drive model of a speed reducer coupled with a high-speed asynchronous motor. This reduces the overall transmission efficiency of the system due to mechanical factors such as the speed reducer's gears. Furthermore, the speed reducer increases the overall size of the drive system, resulting in a low transmission power density. Furthermore, traditional speed reducers require a separate lubrication system, adding complexity and cost. In low-speed, high-torque gearless transmission systems, the industry consensus is that rare earth permanent magnet motors should replace traditional asynchronous motors. Despite the wide variety and availability of permanent magnet motors, existing ones still present certain challenges. The overly complex transmission chain results in low transmission efficiency, high energy consumption, excessively high component temperatures, and a high failure rate, which does not meet the equipment's lifespan performance requirements.

[0003] In order to effectively improve the power density of the low-speed permanent magnet motor, increase the total fluid flow rate in the low-speed permanent magnet motor and make full use of the air volume and cooling oil in the low-speed permanent magnet motor to effectively take away the heat of each component, a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core can be used. N circumferentially excited permanent magnets are installed in the rotor slots, which enhances the magnetic field strength in the low-speed permanent magnet motor and reduces the eddy current loss of the permanent magnet. The temperature of the stator core and stator winding of the low-speed permanent magnet motor is reduced by the cooling oil in the parallel axial oil channels in the stator core. The axial ventilation cooling system in the permanent magnet motor is used to increase the flow rate of cooling gas in the low-speed permanent magnet motor, increase the contact area between the rotor pole body and the cooling gas, and accelerate the fluid velocity around the stator core, stator winding, permanent magnets, rotor pole body, damping bars, damping end rings and end components, effectively reducing the temperature of the stator core, stator winding, permanent magnets, rotor pole body, damping bars, damping end rings and end components, reducing the temperature difference and thermal stress in the axial direction of the low-speed permanent magnet motor, improving the utilization rate of the cooling gas, and enhancing the ability of the low-speed permanent magnet motor to operate safely and stably for a long time. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core, so as to solve the problem of excessive temperature of the stator core, stator winding, rotor pole body, damping bar, damping end ring, permanent magnet and end components caused by unreasonable ventilation design in the stator area and rotor area of ​​traditional low-speed permanent magnet motors, significantly improve the power density of the low-speed permanent magnet motor, increase the total fluid flow in the low-speed permanent magnet motor and make full use of the cooling gas and cooling oil in the low-speed permanent magnet motor to effectively remove the heat of each component, effectively improve the utilization rate of the cooling gas, reduce the temperature of each component and the temperature difference in the axial direction of the motor, and improve the ability of the low-speed permanent magnet motor to operate safely and stably.

[0005] The low-speed permanent magnet motor of the present invention has an oil-cooled axial ventilation cooling system in the stator core, which includes a damping end ring, a damping end ring push-in fan, a damping strip, an oil tank, a stator winding, a stator core, stator interlayer insulation, a permanent magnet, an axial ventilation hole of a support plate, an axial flow fan, a cooling oil outlet, a rotating shaft, a casing, a cooling oil inlet, an air gap, parallel axial oil channels, a stator slot wedge, a rotor circular slot, a rotor pole body, a support plate, and a damping end ring pull-out fan, wherein the axial flow fan is composed of a lower axial flow fan and an upper axial flow fan. Parallel axial oil channels are provided in the stator core, oil tanks are installed at both ends of the stator core, n permanent magnets are installed in the rotor slots, m circular slots are provided on the outer surface of each rotor pole body, a damping bar is installed every other circular slot, and the circular slots between adjacent damping bars are empty, the damping bars are connected to the damping end rings in the end areas on both sides of the rotor pole body, a push-in fan is installed on the outer surface of the damping end ring at one end, and an exhaust fan is installed on the outer surface of the damping end ring at the other end, axial ventilation holes are provided in the support plate, and axial fans are installed on both sides of the rotating shaft.

[0006] The number n of permanent magnets installed in the rotor slots is 2 to 4; the number m of circular grooves on the outer surface of each rotor pole body is 3 to 5; the width of the parallel axial oil channel is 6 mm to 12 mm; the length of the parallel axial oil channel is 10 mm to 16 mm; the flow rate of the cooling oil at the oil tank inlet is 1 m / s to 3 m / s; and the diameter of the axial flow fan is 300 mm to 450 mm.

[0007] Preferably, the cross-sectional area of ​​the parallel axial oil channel at the stator core gradually decreases along the flow direction of the cooling oil, so that the cooling oil flow rate gradually increases along the flow direction of the cooling oil, thereby improving the utilization rate of the cooling oil and further reducing the temperature of the stator core.

[0008] Preferably, the cross section of the parallel axial oil passage at the stator core is changed from rectangular to circular, thereby increasing the surface heat dissipation coefficient of the stator core and further reducing the temperature of the stator core.

[0009] Preferably, the number of the parallel axial oil channels at the bottom of each stator slot is adjusted from one to two, which improves the magnetic field of the stator core yoke and reduces the loss of the stator core while ensuring the cooling effect.

[0010] Preferably, the middle permanent magnet among the three permanent magnets in the rotor slot is a high coercive force permanent magnet, and the permanent magnets on both sides are low coercive force permanent magnets, which further enhances the magnetic field strength in the low-speed permanent magnet motor and improves the power density of the low-speed permanent magnet motor.

[0011] Advantages of the present invention: Conventional high-power-density, low-speed permanent magnet motors suffer from low internal fluid flow and high component temperatures. The present invention provides parallel axial oil passages within the original solid stator, adds oil tanks at both ends of the stator core, replaces the original radially excited single permanent magnet with n circumferentially excited permanent magnets, adds circular grooves to the outer surface of the rotor pole body, installs a damping bar every other circular groove, adds push-in fans and pull-out fans at both ends of the rotor damping end ring, and adds axial fans on both sides of the rotating shaft, thereby forming a low-speed permanent magnet motor with an oil-cooled, axial ventilation cooling system within the stator core. The circumferentially excited n permanent magnets of the low-speed permanent magnet motor with an oil-cooled, axial ventilation cooling system within the stator core can effectively improve the waveform of the sinusoidal magnetic field within the low-speed permanent magnet motor, significantly enhance the magnetic field strength within the low-speed permanent magnet motor, and reduce eddy current losses in the permanent magnets, effectively increasing the power density of the low-speed permanent magnet motor. In terms of ventilation cooling, cooling oil enters the parallel axial oil passages within the stator core from the cooling oil inlet and flows out from the cooling oil outlet, effectively reducing the temperature of the stator core and stator windings, minimizing the axial temperature difference and thermal stress between the stator core and stator windings. This solves the problem of traditional cooling water flowing in a spiral direction along the circumferential surface of the stator core, which leads to increased water temperature and reduced cooling effect. The push-in fan on the outer surface of the damping end ring further increases the flow rate and pressure of the cooling gas. The high-pressure and high-flow cooling gas flows axially in the air gap between the stator core and the rotor pole body, effectively reducing the temperature of the stator core, rotor pole body, damping end ring, and damping bars. The circular grooves formed on the outer surface of the rotor pole body include vacant grooves, which increase the contact area between the cooling gas and the rotor pole body, improve the heat dissipation coefficient of the outer surface of the rotor pole body, reduce the temperature difference of the rotor pole body in the axial direction, and effectively remove the heat from the damping strips around the vacant grooves, further reducing the temperature of the damping strips. Under the action of the exhaust fan, the flow rate of the cooling gas is further accelerated, thereby increasing the flow rate of the cooling gas within the low-speed permanent magnet motor. The low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system within the stator core described in the present invention can effectively improve the power density of the low-speed permanent magnet motor, effectively reduce the volume of the low-speed permanent magnet motor, save manufacturing costs, increase the flow rate and flow velocity of the cooling gas within the low-speed permanent magnet motor, improve the utilization rate of the cooling gas, enhance the ability of the low-speed permanent magnet motor to operate safely and stably, and has higher reliability and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For ease of explanation, the present invention is described in detail with reference to the following specific implementations and accompanying drawings.

[0013] Figure 1 This is a fluid flow diagram in the low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to the present invention.

[0014] Figure 2 This is an axial cross-sectional view of the low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to the present invention.

[0015] Figure 3 This is a top view of the low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system according to the present invention.

[0016] Figure 4 This is a radial cross-sectional view of the low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to the present invention.

[0017] Figure 5 This is a three-dimensional partial enlarged view of the rotor area of ​​the low-speed permanent magnet motor with the stator core oil-cooled axial ventilation cooling system described in the present invention.

[0018] Figure 6 This is a partial enlarged view of the radial cross section of the rotor area of ​​the low-speed permanent magnet motor with the stator core oil-cooled axial ventilation cooling system according to the present invention.

[0019] Figure 7 This is an axial cross-sectional view of a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to a second specific embodiment of the present invention.

[0020] Figure 8 This is a top view of a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to a third specific embodiment of the present invention.

[0021] Figure 9 This is a top view of a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to a fourth specific embodiment of the present invention.

[0022] Figure 10 This is a top view of a low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core according to a fifth specific embodiment of the present invention.

[0023] In the figure: 1-damping end ring, 2-damping end ring push-in fan, 3-damping strip, 4-oil tank, 5-stator winding, 6-stator core, 7-stator interlayer insulation, 8-permanent magnet, 9-support plate axial ventilation hole, 10-axial flow fan, 11-cooling oil outlet, 12-rotating shaft, 13-housing, 14-cooling oil inlet, 15-air gap, 16-stator axial oil channel, 17-stator slot wedge, 18-circular slot, 19-rotor pole body, 20-support plate, 21-damping end ring pull-out fan. The arrows in the figure indicate the flow direction of the fluid within a low-speed permanent magnet motor with an internal stator core oil-cooled axial ventilation cooling system. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0025] Specific implementation method 1: Combination Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 This embodiment is described, which includes a damping end ring 1, a damping end ring push-in fan 2, a damping strip 3, an oil tank 4, a stator winding 5, a stator core 6, a stator interlayer insulation 7, a permanent magnet 8, an axial ventilation hole of a support plate 9, an axial flow fan 10, a cooling oil outlet 11, a rotating shaft 12, a casing 13, a cooling oil inlet 14, an air gap 15, a parallel axial oil channel 16, a stator slot wedge 17, a circular groove 18, a rotor pole body 19, a support plate 20, and a damping end ring pull-out fan 21. The axial flow fan 10 is composed of a lower axial flow fan 10-1 and an upper axial flow fan 10-2. Parallel axial oil channels 16 are provided in the stator core 6, oil tanks 4 are installed on both ends of the stator core 6, n permanent magnets 8 are installed in the rotor slots, m circular grooves 18 are provided on the outer surface of each rotor pole body 19, a damping bar 3 is installed every other circular groove 18, and the circular grooves 18 between adjacent damping bars 3 are empty, the damping bars 3 are connected to the damping end rings 1 in the end areas on both sides of the rotor pole body 19, a push-in fan 2 is installed on the outer surface of the damping end ring 1 at one end, and an exhaust fan 21 is installed on the outer surface of the damping end ring 1 at the other end, axial ventilation holes 9 are provided in the support plate 20, and axial fans 10 are installed on both sides of the rotating shaft 12.

[0026] The number n of permanent magnets 8 installed in the rotor slots is 2 to 4, and is 3 in this embodiment; the number m of circular grooves 18 opened on the outer surface of each rotor pole body 19 is 3 to 5, and is 3 in this embodiment; the width of the parallel axial oil passages 16 is 6 mm to 12 mm, and is 8 mm in this embodiment; the length of the parallel axial oil passages 16 is 10 mm to 16 mm, and is 12 mm in this embodiment; the flow rate of the cooling oil at the inlet of the oil tank 4 is 1 m / s to 3 m / s, and is 2 m / s in this embodiment; the diameter of the axial flow fan 10 is 300 mm to 450 mm, and is 400 mm in this embodiment.

[0027] A low-speed permanent magnet motor with an oil-cooled, axial ventilation cooling system within the stator core features parallel axial oil passages 16 within the original solid stator core, with oil tanks 4 added to both ends of the stator core. The original radially excited, single permanent magnet is replaced with n circumferentially excited permanent magnets 8. Circular grooves 18 are added to the outer surface of the rotor pole body 19, with a damping bar 3 installed every other circular groove 18. A push-in fan 2 and an exhaust fan 21 are added at both ends of the rotor damping end ring 1, and axial fans 10 are added on both sides of the rotating shaft 12. The n circumferentially excited permanent magnets 8 effectively improve the waveform of the sinusoidal magnetic field within the low-speed permanent magnet motor, significantly enhancing the magnetic field strength within the low-speed permanent magnet motor. They also reduce eddy current losses in the permanent magnets 8, effectively increasing the power density of the low-speed permanent magnet motor. In terms of ventilation cooling, cooling oil enters parallel axial oil passages 16 from cooling oil inlet 14. Since the cooling oil in parallel axial oil passages 16 simultaneously flows in parallel along the axial direction, it can effectively remove heat from stator core 6, reducing the temperature difference and thermal stress of stator core 6 in the axial direction, increasing the heat dissipation coefficient of the stator core 6 surface, and significantly reducing the temperature of stator core 6. This solves the problem of traditional cooling water flowing in a spiral direction along the circumferential direction of the stator core outer surface, which causes water temperature to rise and the cooling effect to deteriorate. Heat from stator winding 5 can also be removed by cooling oil after passing through stator core 6, further reducing the temperature of stator winding 5, which is the most seriously heated. Cooling oil flows into cooling oil inlet 14 and out of cooling oil outlet 11. The flow rate of cooling oil can be further accelerated under the action of gravity, thereby improving the utilization rate of cooling oil.Under the action of the lower axial flow fan 10-1 on the outer surface of the rotating shaft 12, the cooling gas flows in the axial direction through the axial ventilation holes 9 in the support plate 20. After reaching the upper axial flow fan 10-2 on the outer surface of the rotating shaft 12, the flow rate and pressure of the cooling gas are further increased under the action of the upper axial flow fan 10-2. The cooling gas first cools the upper stator end winding, reduces the temperature of the upper stator end winding, and then reaches the push-in fan 2 on the outer surface of the damping end ring 1. Under the action of the push-in fan 2, the flow rate and pressure of the cooling gas are further increased. The high-pressure and large-flow cooling gas flows in the axial direction in the air gap between the stator core 6 and the rotor pole body 19, which can effectively take away the heat of the cooling stator core 6, the rotor pole body 19, the damping end ring 1, and the damping bar 3, thereby reducing the temperature of the stator core 6, the rotor pole body 19, the damping end ring 1, the damping bar 3 and the permanent magnet 8. Since there are vacant grooves in the circular grooves 18 opened on the outer surface of the rotor pole body 19 and the damping strips 3 are not installed, the contact area between the cooling gas and the rotor pole body 19 is increased, the heat dissipation coefficient of the outer surface of the rotor pole body 19 is improved, and the temperature difference of the rotor pole body 19 in the axial direction is reduced. It can also effectively take away the heat of the damping strips 3 around the vacant grooves, further reducing the temperature of the damping strips 3. After the cooling gas flowing out of the air gap between the stator core 6 and the rotor pole body 19 reaches the exhaust fan 21, the flow speed of the cooling gas is further accelerated under the action of the exhaust fan 21, the pressure of the cooling gas is increased, and the flow rate of the cooling gas in the low-speed permanent magnet motor is increased. This part of the cooling gas can effectively reduce the temperature of the lower stator end winding and then reach the lower axial flow fan 10-1 on the outer surface of the rotating shaft 12 again, thereby completing the oil-cooled axial ventilation cooling cycle in the entire stator core. A low-speed permanent magnet motor with an oil-cooled axial ventilation cooling system in the stator core can effectively improve the power density of the low-speed permanent magnet motor, effectively reduce the volume of the low-speed permanent magnet motor, save manufacturing costs, significantly reduce the temperature of the stator core 6, stator winding 5 and permanent magnet 8, increase the flow rate of cooling gas in the low-speed permanent magnet motor, improve the flow speed and utilization rate of the cooling gas, and enhance the ability of the low-speed permanent magnet motor to operate safely and stably.

[0028] Specific implementation method 2: Combination Figure 7 This embodiment differs from the first embodiment in that the cross-sectional area of ​​the parallel axial oil passages 16 in the stator core 6 gradually decreases along the cooling oil flow direction. This gradually increases the cooling oil flow rate along the cooling oil flow direction, improving cooling oil utilization and further reducing the temperature of the stator core 6. The remaining components and connections are the same as those in the first embodiment.

[0029] Specific implementation method three: Combination Figure 8This embodiment differs from the first embodiment in that the cross-section of the parallel axial oil passages 16 in the stator core 6 is changed from a rectangular to a circular shape, thereby increasing the surface heat dissipation coefficient of the stator core 6 and further reducing the temperature of the stator core 6. The remaining components and connections are the same as those in the first embodiment.

[0030] Specific implementation method four: Combination Figure 9 This embodiment differs from the first embodiment in that the number of parallel axial oil passages 16 at the bottom of each stator slot is increased from one to two. This improves the magnetic field at the yoke of the stator core 6 while maintaining cooling efficiency, thereby reducing losses in the stator core 6. The remaining components and connections are the same as those in the first embodiment.

[0031] Specific implementation method five: Combination Figure 10 This embodiment differs from the first embodiment in that the central permanent magnet 8-1 of the three permanent magnets 8 in the rotor slots is a high-coercivity permanent magnet, while the two side permanent magnets 8-2 are low-coercivity permanent magnets. This further enhances the magnetic field strength within the low-speed permanent magnet motor and improves its power density. The remaining components and connections are the same as those in the first embodiment.

[0032] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system, characterized in that: The invention comprises a damping end ring (1), a damping end ring push-in fan (2), a damping strip (3), an oil tank (4), a stator winding (5), a stator core (6), stator interlayer insulation (7), a permanent magnet (8), an axial ventilation hole of a support plate (9), an axial flow fan (10), a cooling oil outlet (11), a rotating shaft (12), a housing (13), a cooling oil inlet (14), an air gap (15), a parallel axial oil passage (16), a stator slot wedge (17), a circular slot (18), a rotor pole body (19), a support plate (20), and a damping end ring extraction fan (21). The axial flow fan (10) is composed of a lower axial flow fan (10-1) and an upper axial flow fan (10-2). A plurality of axial flow fans are provided in the stator core (6). There are parallel axial oil passages (16), oil tanks (4) are installed at both ends of the stator core (6), n permanent magnets (8) are installed in the rotor slots, m circular grooves (18) are opened on the outer surface of each rotor pole body (19), a damping strip (3) is installed every other circular groove (18), and the circular grooves (18) between adjacent damping strips (3) are vacant, the damping strips (3) are connected to the damping end rings (1) in the end areas of both sides of the rotor pole body (19), a push-in fan (2) is installed on the outer surface of the damping end ring (1) at one end, and an exhaust fan (21) is installed on the outer surface of the damping end ring (1) at the other end, an axial ventilation hole (9) is opened in the support plate (20), and axial fans (10) are installed on both sides of the rotating shaft (12).

2. The low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system according to claim 1, characterized in that: The number n of permanent magnets (8) installed in the rotor slots is 2 to 4; the number m of circular grooves (18) opened on the outer surface of each rotor pole body (19) is 3 to 5; the width of the parallel axial oil passages (16) is 6 mm to 12 mm; the length of the parallel axial oil passages (16) is 10 mm to 16 mm; the flow rate of the cooling oil at the inlet of the oil tank (4) is 1 m / s to 3 m / s; and the diameter of the axial flow fan (10) is 300 mm to 450 mm.

3. The low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system according to claim 1, characterized in that: The cross-sectional area of ​​the parallel axial oil passage (16) at the stator core (6) gradually decreases along the flow direction of the cooling oil.

4. The low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system according to claim 1, characterized in that: The cross section of the parallel axial oil passage (16) at the stator core (6) is circular.

5. The low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system according to claim 1, characterized in that: The number of the parallel axial oil passages (16) at the bottom of each stator slot is two.

6. The low-speed permanent magnet motor with an oil-cooled stator core and an axial ventilation cooling system according to claim 1, characterized in that: The permanent magnet (8-1) in the middle of the three permanent magnets (8) in the rotor slot is a high-coercive force permanent magnet, and the permanent magnets (8-2) on both sides are low-coercive force permanent magnets.

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